편평세포암종 임파절 전이에 대한 인공 신경망 시스템의 진단능 평가

허민석,박태원,박상욱,유동수,이삼선,최순철 大韓口腔顎顔面 放射線學會 1999 Imaging Science in Dentistry Vol.29 No.1

Purpose: The purpose of this study was to evaluate cervical lymph node metastasis of oral squamous cell carcinoma patients by MRI film and neural network system. Materials and Methods: The oral squamous cell carcinoma patients(21 patients, 59 lymph nodes) who have visited SNU hospital and been taken by MRI, were included in this study. Neck dissection operations were done and all of the cervical lymph nodes were confirmed with biopsy. In MR images, each lymph node were evaluated by using 6 MR imaging criteria(size, roundness, heterogeneity, rim enhancement, central necrosis, grouping) respectively. Positive predictive value, negative predictive value, and accuracy of each MR imaging criteria were calculated. At neural network system, the layers of neural network system consisted of 10 input layer units, 10 hidden layer units and 1 output layer unit. 6 MR imaging criteria previously described and 4 MR imaging criteria (site I-node level II and submandibular area, site II-other node level, shape I-oval, shape II-bean) were included for input layer units. The training files were made of 39 lymph nodes(24 metastatic lymph nodes, 10 non-metastatic lymph nodes) and the testing files were made of other 20 lymph nodes(10 metastatic lymph nodes, 10 non-metastatic lymph nodes). The neural network system was trained with training files and the output level (metastatic index) of testing files were acquired. Diagnosis was decided according to 4 different standard metastatic index-68, 78, 88, 98 respectively and positive predictive values, negative predictive values and accuracy of each standard metastatic index were calculated. Results: In the diagnosis of using single MR imaging criteria, the rim enhancement criteria had highest positive predictive value (0.95) and the size criteria had highest negative predictive value(0.77). In the diagnosis of using single MR imaging criteria, the highest accurate criteria was heterogeneity (accuracy : 0.81) and the lowest one was central necrosis (accuracy : 0.59). In the diagnosis of using neural network systems, the highest accurate standard metastatic index was 78, and that time, the accuracy was 0.90. Neural network system was more accurate than any other single MR imaging criteria in evaluating cervical lymph node metastasis. Conclusion: Neural network system has been shown to be more useful than any other single MR imaging criteria. In future, Neural network system will be powerful aiding tool in evaluating cervical node metastasis.

전압형 PWM 컨버터의 전압 센서리스 제어

허태원,신동률,안인모,우정인 동아대학교 정보기술연구소 2000 情報通信硏究所論文誌 Vol.8 No.1

This paper presents a control scheme for a three-phase PWM converter system without any voltage sensors. Two input currents and one load current are measured. In a general PWM converter system, the required AC input and DC output voltage values in order to control the converter are estimated using the differential equations of the converter from the measured input currents and load current values in the switch modes of the converter circuit. The PI controller is used as DC voltage controller and sinusoidal tracking controller which tracks directly AC input current is used as input current controller. The proposed method is verified by simulations. This paper describes the estimation method and configuration of the controller, and discusses steady state and transient performances of the converter.

당뇨병성 합병증을 가진 환자에서 혈증 Erythropoietin 농도

김동규,유기동,허광식,김상용,윤성호,조영신,권용은,김태원,김건영,정종훈,배학연 조선의대 1998 The Medical Journal of Chosun University Vol.23 No.1

Correction: Direct characterization of graphene doping state by <i>in situ</i> photoemission spectroscopy with Ar gas cluster ion beam sputtering

Yun, Dong-Jin,Kim, Seyun,Jung, Changhoon,Lee, Chang-Seok,Sohn, Hiesang,Won, Jung Yeon,Kim, Yong Su,Chung, JaeGwan,Heo, Sung,Kim, Seong Heon,Seol, Minsu,Shin, Weon Ho The Royal Society of Chemistry 2018 Physical chemistry chemical physics Vol.20 No.4

<P>Correction for ‘Direct characterization of graphene doping state by <I>in situ</I> photoemission spectroscopy with Ar gas cluster ion beam sputtering’ by Dong-Jin Yun <I>et al.</I>, <I>Phys. Chem. Chem. Phys.</I>, 2018, 20, 615-622.</P>

비인강을 침범한 관통성 이물 2예

박동준,박상유,허원,최해명 연세대학교 원주의과대학 2000 원주의대논문집 Vol.13 No.1

당뇨병성 합병증을 가진 환자에서 혈중 Erythropoietin 농도

김동규,유기동,허광식,김상용,윤성호,조영신,권용은,김태원,김건영,정종훈,배학연 朝鮮大學校 附設 醫學硏究所 1998 The Medical Journal of Chosun University Vol.23 No.1

연구 배경 : 고혈당성에 의한 산화환원반응 이상(가저산소증)이 조절 되지않는 당뇨병의 특징으로 혈관과 신경 기능에 대한 진성 저산소증의 효과와 유사하며, 당뇨 합병증의 병태생리에 중요한 역할을 한다. 고혈당이 있는 인슐린 비의존형 당뇨병 환자에서 인슐린 수준이 정상이듯이, 빈혈이 있는 당뇨병 환자에서 EPO의 농도는 실제 혈색소 농도의 감소비율과 차이가 있을 것이라 추측된다. Friedman 등은 당뇨병성 합병증 원인 인자로 가저산소증(pseudohypoxia) 또는 저산소증(hypoxia)을 제기하였고 이런 인자들이 EPO의 상대적 또는 절대적 결핍에 의한 것임을 보고하였다. 방법 : EPO-Trac^(TM 125)I RIA kit을 이용하여 방사면역측정법으로 EPO 수준을 검사하였다. 전혈 3㎖을 5-10㎖ 시험관에 정맥 채혈하였으며, 용혈과 장기간의 보존을 위하여 원심분리를 즉시 시행하여 혈청을 영하 200C에서 냉동 보관 후 일괄적으로 검사 결과를 얻었다. 결과 : 1996년 9월부터 1997년 2월까지 조선대학교 부속병원 내과에 입원한 2형 당뇨병 환자 63례를 대상으로 하여 다음과 같은 결과를 얻었다. 1) 당뇨병성 합병증이 없는 군과 있는 군간의 혈색소, 혈중 EPO농도의 차이는 유의한 차이가 있었으며 혈색소의 감소율보다 혈중 EPO의 감소율이 더 높았다. 2) 당뇨병성 망막증의 유무에 따른 혈색소 농도의 차이는 유의한 차이가 없었으나 혈중 EPO농도는 유의한 차이가 있었다. 증식성군에서만 혈중 EPO의 감소비율이 혈색소에 비해 높았다. 3) 당뇨병성 신증의 유무에 따른 혈색소, 혈중 EPO농도는 유의한 차이가 있었고 혈색소 감소율에 비해 EPO농도의 감소율이 높았다. 신증의 중증도에 따른 혈색소, EPO의 차이는 미세알부민뇨군을 제외하고는 유의한 차이를 보였고 혈색소 감소율에 비해 EPO의 감소율이 더높았다. 4) 당뇨병성 신경병증의 유무에 따른 혈색소 농도의 차이는 유의한 차이가 없었으며 EPO농도는 유의한 차이를 보였다. 혈색소와 EPO의 감소비율은 비슷하였다. 신경병증의 중등도에 따른 혈색소와 EPO농도의 변화는 유의한 차이가 없었으나 stage 3에서는 혈색소감소율보다 EPO감소율이 더높았다. 결론 : 당뇨병성 합병증을 가진 환자에서 빈혈의 정도는 대부분 혈청 EPO치의 절대적 감소에 의함을 간접적으로 밝혀낼 수 있었으며 차후 더 많은 대상으로 비교 분석이 필요하리라 사료된다. Background: Hyperglycemic-induced redox(pseudohypoxia) imbalance is a characteristic feature of poorly controlled diabetes that mimics the effects of true hypoxia on vascular and neural functions and plays an important role on the pathogenesis of diabetic complications. As is true for apparently "normal" insulin levels typically found in NIDDM even in the presence of hyperglycemia, a "normal" erythropoietin level in an anemic diabetic subject may be disproportionally low for the actual red cell mass. Therefore, Friedman et al suggested that pseudohypoxia or hypoxia as an etiological factor of diabetic complications are due to absolute or relative erythropoietin deficiency Method: EPO-TracTM 125I RIA kit was used for the quantitative determination of erythropoietin(EPO) in serum by radioimmunoassay. An adequate sample of blood (3ml whole blood) was collected aseptically by venipuncture in a 5~10ml glass tube to yield a minimum of 400 L of serum per assay. The serum was promptly removed from the clot by centrifugation in order to avoid hemolysis. Then to increase its storage time it was frozen at -200C in a nonself defrosting freezer. Finally, tests were undertaken simultaneously Results We studied 63 cases with diabetes mellitus, who were admitted to Chosun University Hospital from September, 1996 to February, 1997 at the Department of Internal Medicine. We defined the control group, as diabetic patients who did not have anemia(<13mg/dl), diabetic complications(retinopathy, nephropathy, neuropathy) and the remainders were defined as the experimental group(we excluded anemic patients, who had secondary causes of anemia and diabetic patients with end stage renal disease)Data were as follow 1) The relationship of Hb and the 24hr urine protein between diabetic patients with and without complications significantly differed(p=0.02, < 0.001 respectively), but the Hb level was poorly related between diabetic patients with and without retinopathy(except in preproliferative, proliferative subgroups) and neuropathy. 2) Subgroups of patients with diabetic complications had higher 24hr urine protein than patients without diabetic complications, except stage I diabetic neuropathy 3) The EPO level was significantly different between diabetic patients with and without complications. 4) The correlation between EPO and Hb was significantly different, especially in diabetic patients with retinopathy and nephropathy according to severity of diabetic complications, compared with patients who did not have diabetic complications such as retinopathy and nephropathy. Conclusion: We know that anemia induced by diabetic complications is due to relative EPO deficiency than absolute EPO deficiency, and further evaluation and studies are needed on many cases in the future

태양광 발전전력을 입력으로한 DC/DC 컨버터의 일정출력제어

조용길,허태원,신동률,조광승,우정인 東亞大學校 大學院 2000 大學院論文集 Vol.25 No.-

In this paper, it is proposed to constant power control of solar power system. The solar power system has disadvantage that low power density and variable power output. Proposed strategy is controled by DC/DC converter using phase shift PWM and I-PD type control applying type 1 digital system. The validity of proposed control strategy is verified from simulations results using PSIM.

방사선조사 후 유표피암종세포내 칼슘농도의 변화와 apoptosis 발현에 관한 연구

이삼선,문제운,허민석,박태원,유동수,최순철 大韓口腔顎顔面 放射線學會 1999 Imaging Science in Dentistry Vol.29 No.1

Purpose: Ionizing radiations have been reported as an apoptosis initiating stimulus in various cells and it has established that sustained elevations in [Ca²+] can lead to DNA fragmentation by Ca²+-dependent endonucleases, ultimately resulting in apoptotic cell death. The previous experiments have been reported by using primarily thymocytes and lymphocytes and the change of [Ca²+] was measured only by minutes or hours respectively. We need to evaluate [Ca²+] in both several minutes and hours after irradiation of radiation of radiation therapy and verify the apoptotic cells. Materials and Methods: We have measured [Ca²+] in human gingival epitheloid cancer cell with 10 Gy irradiation, at minutely intervals and hourly intervals using digitized video-intensified fluorescence microscopy and the fluorescent Ca²+ indicator dye, fura-2. In order to find out that the transient rise in [Ca²+] could induced apoptosis, cells were incubated for 1 hour at 37℃ with TdT enzyme, rinsed and resuspended containing fluorescence and observed under a confocal fluorescence microscope. MTT assay was done to determine cell activity and LDH assay was done to determine the amount of necrotic cells. Results: After irradiation, the transient and temporal increasing of [Ca²+] in the KB cells was founded. Though, there was no change in the intracellular [Ca²+] at 30 minutes and 2 hours after irradiation. We could detect of DNA fragmented cells at 4 hours after 10 Gy irradiated cells. There were no significant differences between 4 hour, 1 day, 3 day cells. There were no significant differences in MTT and LDH assay between the irradiated group and the control group after 4 hours and 1 day. Though after 3 days there were differences in MTT and LDH assay between the irradiated group was significantly decreased than the control group, in LDH assay the number of necrotic cell death of the irradiated was higher than the control group. Conclusion: In KB cells there were incipient and temporal increasing of the [Ca²+] with 10 Gy irradiation and the apoptosis was founded from 4 hours later which was earlier than seeing of the change of the amount of the cellular ability and necrosis.(J Korean Oral Maxillofac Radiol 1999:29:109-117)

전산화단층사진을 이용한 타액선의 정량분석에 관한 연구

최순철,박태원,이상철,유동수,허민석,이삼선 大韓口腔顎顔面 放射線學會 1999 Imaging Science in Dentistry Vol.29 No.1

Purpose: The purpose of this study was to calculate the size and CT number of both normal parotid and submandibular gland, and evaluate their relation to sex, age and obesity using computed tomography. Materials and Methods: The computed tomography was performed parallel to the Frankfurt plane in 46 subjects with healthy salivary gland. The subjects were divided into the three groups(young, middle, old) according to their ages. The size of salivary gland was determined as maximum cross-sectional area and the CT number of salivary gland was determined as the mean CT number of three ROI's. The body mass index was calculated from weight and height. Results: The mean maximum cross-sectional area was 7.79(±1.25) ㎠ on parotid gland and 4.12(±0.83) ㎠ on submandibular gland. The mean CT number was -4.43(±23.87) HU on parotid gland and 50.01(±15.63) HU on submandibular gland. There was decreasing pattern of the maximum cross-sectional area of submandibular gland and the CT number of both parotid and submandibular gland according to age(p<0.50). As the body mass index increased, the maximum cross-sectional area of parotid gland increased and CT number of both parotid and submandibular gland decreased(p<0.05). The maximum cross-sectional area of submandibular gland in male was larger than that in female(p<0.05). As the maximum cross-sectional area and CT number of left salivary gland increased, those of right gland increased(p<0.05). Conclusion: Intra-individual differences in salivary gland size and CT number is considered in the age and individual obesity.(J Korean Oral Maxillofac Radiol 1999:29:207-219)

진상전류 추정에 의한 태양광 발전시스템의 최대출력제어

우정인,신동률,허태원,박지호,노인배 東亞大學校 大學院 1997 大學院論文集 Vol.22 No.-

Photovoltaic power may vary depending on the various solar cell has an optimal generating point to be able to get the maximum power tracking, in order to get the more power recovery on the switching control system. However the V-I characteristics of the solar array at the frequency have hysteresis, in such high frequency region the conventional controller based on no hysteresis can not be responsible for control of the photovoltaic power system. Therefore, in this paper we proposed a maximum power tracking technique to improve the operation in the region of high frequency[5KHz-30KHz] with added C-R differential circuit for zero cross switching. The distinguishing characteristics of this method is to be controlled by the estimated values of resistive current and sensed photovoltaic terminal voltage do not depend on the operating frequency. the experimental result of the power system is controlled by the proposed sampling.